Add data_source_backup_dr_data_source_.go.tmpl and test file (GoogleCloudPlatform#11935)

Author: Matt-Ng

mmv1/third_party/terraform/provider/provider_mmv1_resources.go.tmpl

@@ -37,6 +37,7 @@ var handwrittenDatasources = map[string]*schema.Resource{
 	"google_backup_dr_management_server":				backupdr.DataSourceGoogleCloudBackupDRService(),
 	"google_backup_dr_backup_plan_association":			backupdr.DataSourceGoogleCloudBackupDRBackupPlanAssociation(),
 	"google_backup_dr_backup_plan":						backupdr.DataSourceGoogleCloudBackupDRBackupPlan(),
+	"google_backup_dr_data_source":						backupdr.DataSourceGoogleCloudBackupDRDataSource(),
 	{{- end }}
 	"google_beyondcorp_app_connection":                 beyondcorp.DataSourceGoogleBeyondcorpAppConnection(),
 	"google_beyondcorp_app_connector":                  beyondcorp.DataSourceGoogleBeyondcorpAppConnector(),